From the second her baby brother was born, Vivi—16 and totally obsessed—decided she wasn’t just his sister, she was his second mom. Their mom didn’t even mind; in fact, she loved it. “I haven’t had this much free time since Vivi was in diapers,” she joked, sipping her coffee while Vivi took full control of the baby’s world.

Every morning, Vivi would burst into the nursery before their mom could even get out of bed. “Good moooorning, my little squish muffin!” she’d sing in her high-pitched baby voice, scooping him up like he was made of glass. “Who’s the cutest baby in the whole wide world? Oh wait—it’s you, duh!” Then she’d gently bounce him while picking out his outfit of the day, laying out tiny overalls, graphic onesies, and mini socks with animal faces.

She took him everywhere. To Starbucks, the mall, Target—he was practically her accessory. Her friends joked, “Vivi, that’s not your baby!” but she’d just laugh and say, “He basically is. I mean, look at him. We even match today!”

She had a routine, too: stroller walks around the block with a baby bottle in the side pocket, diaper bag slung over her shoulder, and her phone full of baby TikToks and Instagram stories of him giggling or babbling.

And honestly, the baby loved it. His tiny fingers would grip her hoodie strings or her pinky finger, his eyes lighting up when she talked to him. Vivi would lean in close and whisper, “You better not grow up too fast, little dude. I’m keeping you tiny forever.”